1. Field of the Invention
The present invention relates to charger protection devices, particularly to a charger protection device used to protect batteries and chargers when at extreme temperatures.
2. Description of Related Art
Charging a battery should only be done when the battery is in an appropriate temperature range. Too high or too low of temperature can damage the battery and the charger. Thus, a protecting device is often used in a charging circuit to automatically stop charging the battery when the battery becomes too hot or too cold.
Referring to FIG. 2, a typical charger protection device 10 includes a controlling IC (integrate circuit) 101, a switch 102 and a thermistor 103. The controlling IC 101 and the switch 102 are installed in a charger 11. The controlling IC 101 is electronically connected to the switch 102 to control the switch 102. The thermistor 103 is incorporated in a battery 12.
In use, the charger 11 is electronically connected to a power supply (not shown). The battery 12 is electronically connected to the charger 11, and the controlling IC 101 is electronically connected to the thermistor 103. When the switch 102 is turned on, the power supply charges the battery 12 via the charger 11. Since the resistance of the thermistor 103 changes in accordance with the temperature thereof, the controlling IC 101 can detect the temperature of the battery 12 via measuring the resistance of the thermistor 103. In the charging process, when the temperature of battery 12 changes, the resistance of the thermistor 103 also changes. The controlling IC 101 detects the temperature of the battery 12 according to the resistance of the thermistor 103. If the temperature of the battery 12 is too high or too low, the controlling IC 101 automatically turns off the switch 102 to stop the charging process, thus protects the charger 11 and the battery 12.
However, in use of the typical charger protection device 10, if the resistance of the thermistor 103 changes too frequently according to the temperature, the controlling IC 101 may crash because of being overloaded with calculations. When the controlling IC 101 crashes, it cannot detect the temperature of the battery 12 and control the switch 102. Thus, the charger 11 and the battery 12 may be damaged by high or low temperatures during charging.
Therefore, a new charger protection device is desired in order to overcome the above-described shortcomings.